internal/core/adt: fix disjunction bug

Default should return unmarked disjuncts, instead
of an error.

Fixes #1304
Fixes #1257

Signed-off-by: Marcel van Lohuizen <[email protected]>

Change-Id: Idfe0302ede7a35cac7dfbbbf0c27242ebb1c3b32
Signed-off-by: Marcel van Lohuizen <[email protected]>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/527316
Unity-Result: CUEcueckoo <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Paul Jolly <[email protected]>

Author: mpvl

cmd/cue/cmd/testdata/script/export_defaulterr.txt

@@ -0,0 +1,26 @@
+#Issue 1304
+
+! cue export --out json x.cue
+cmp stdout expect_stdout_json
+cmp stderr expect_stderr_json
+
+! cue export --out cue x.cue
+cmp stdout expect_stdout_cue
+cmp stderr expect_stderr_cue
+
+! cue export --out yaml x.cue
+cmp stdout expect_stdout_yaml
+cmp stderr expect_stderr_yaml
+
+-- x.cue --
+toto: value: *_|_ | (*"toto" | string)
+
+-- expect_stdout_cue --
+-- expect_stderr_cue --
+toto.value: incomplete value "toto" | string
+-- expect_stdout_json --
+-- expect_stderr_json --
+toto.value: incomplete value "toto" | string
+-- expect_stdout_yaml --
+-- expect_stderr_yaml --
+toto.value: incomplete value "toto" | string

cue/types_test.go

@@ -1562,14 +1562,20 @@ func TestDefaults(t *testing.T) {
 		ok:    true,
 	}, {
 		value: `{a:1}&{b:2}`,
-		def:   `({a:1} & {b:2})`,
+		def:   `{a:1,b:2}`,
 		val:   ``,
 		ok:    false,
+	}, {
+		value: `*_|_ | (*"x" | string)`,
+		def:   `"x" | string`,
+		val:   `"x"|string`,
+		ok:    false,
 	}}
 	for _, tc := range testCases {
 		t.Run(tc.value, func(t *testing.T) {
 			v := getInstance(t, "a: "+tc.value).Lookup("a")
 
+			v = v.Eval()
 			d, ok := v.Default()
 			if ok != tc.ok {
 				t.Errorf("hasDefault: got %v; want %v", ok, tc.ok)

internal/core/adt/default.go

@@ -54,13 +54,6 @@ func (v *Vertex) Default() *Vertex {
 
 		switch d.NumDefaults {
 		case 0:
-			if d.HasDefaults {
-				v = &Vertex{
-					Parent:    v.Parent,
-					status:    Finalized,
-					BaseValue: &Bottom{},
-				}
-			}
 			return v
 		case 1:
 			w = d.Values[0]